Photopolymerizable, positive working, peel developable, single sheet color proofing system

ABSTRACT

This invention relates to positive working photopolymerizable sheet constructions which, upon exposure to an actinic radiation source through a screened image, can accurately reproduce said image. The construction is useful as a color proofing film which can be employed to accurately predict the image quality from a lithographic printing process.

CROSS REFERENCE TO RELATED APPLICATION

THIS APPLICATION IS A CONTINUATION-IN-PART OF U.S. PATENT APPLICATIONSER. NO. 07/220,479, FILED JULY 18, 1988 NOW U.S. PAT. NO. 4,895,787WHICH IS INCORPORATED HEREIN BY REFERENCE.

BACKGROUND OF THE INVENTION

In the graphic arts, it is desirable to produce a three or more colorproof to assist in correcting a set of color separation films prior tousing them to produce printing plates. The proof should reproduce thecolor quality that will be obtained during the printing process. Theproof must be a consistent duplicate of the desired halftone image.Visual examination of a color proof should show the color rendition tobe expected from press printing using the color separations and anydefects on the separations which might need to be altered before makingthe printing plates.

Color proofing sheets for multicolored printing can be made by using aprinting press or proof press. This requires that all of the actualprinting steps be performed. Therefore, this conventional method ofcolor proofing is costly and time consuming.

Photoimaging processes can also be used to produce a color proof. Thereare two general types of photoimaging methods; namely the overlay typeand the single sheet type.

In the overlay type of color proofing method, an independent transparentplastic support is used for producing an image of each color separationfilm by applying a photosensitive solution of the corresponding color. Aplurality of such supports carrying images of the corresponding colorsare then superimposed upon each other over a white sheet to produce acolor proofing composite. The primary advantage of the overlay method isthat proofs can be made quickly and can serve as a progressive proof bycombining any two or three colors in register. However, this type ofcolor proofing method has the disadvantage that the superimposed plasticsupports tend to darken the color proofing sheet. As a result, theimpression of the color proofing composite thus prepared is vastlydifferent from that of copies actually obtained with conventionalprinting presses and with proof presses. Examples of such overlayapproaches are contained in U.S. Pat. Nos. 3,136,637; 3,211,553; and3,326,682.

In the single sheet type of color proofing method, a color proofingsheet is prepared by successively producing images of different colorsfrom different color separation films on a single receiver sheet. Thiscan be accomplished by sequentially applying colorants or colored,photosensitive layers to a single opaque support. This method moreclosely resembles the actual printing process and eliminates the colordistortion inherent in the overlay system. Examples of such single sheetapproaches are contained in U.S. Pat. Nos. 3,671,236; 4,260,673;4,366,223; 4,650,738; 4,656,114; and 4,659,642.

U.S. Pat. No. 3,574,049 provides a thermal transfer process for printinga design on a final support which comprises (a) printing a design onto atemporary support, (b) superimposing the temporary support and the finalsupport, (c) applying heat and/or pressure to the superimposed structureformed in (b), and (d) separating the temporary support from the finalsupport which retains the printed design. The affinity of the matter ofthe design towards the final support is greater than its affinitytowards the temporary support. This process has the disadvantage of aprinting step.

Various processes for producing single sheet color proofs of an imageembodying thermal transfer and photopolymerization techniques are known,for example, from U.S. Pat. Nos. 3,060,023; 3,060,024; 3,060,025;3,481,736; and 3,607,264. In these processes, a photopolymerizable layercoated on a suitable support is imagewise exposed through a colorseparation film. The surface of the exposed layer is then pressed intocontact with an image receptive surface of a separate element. At leastone of the said elements is heated to a temperature above the transfertemperature of the unexposed portions of the layer. The two elements arethen separated, whereby the thermally transferrable, unexposed, imageareas of the composite transfer to the image receptive element. If theelement is not precolored, the tacky unexposed image may now beselectively colored with a desired toner. The colored matterpreferentially adheres to the clear unpolymerized material.

In U.S. Pat. No. 3,721,557, a method for transferring colored images isclaimed which provides a stripping layer coated between a photosensitiveelement and a support. When the photosensitive layer is exposed toactinic light and developed, the more soluble portions are selectivelyremoved to produce a visible image. The image carrying support ispressed against a suitable adhesive coated receptor member and thecarrier support is subsequently stripped to accomplish the transfer ofthe image. A fresh layer of adhesive must be applied to the receptor foreach subsequent transfer.

U.S. Pat. No. 4,596,757 provides a method for transferring images orsolid colors which are subsequently imaged. The photosensitive materialcomprises a carrier support having sequentially disposed thereon arelease layer; a colored, photopolymerizable layer; and an adhesivelayer. The material can undergo exposure, lamination to a temporarysupport, wet development, and then lamination to a receptor sheet.Alternatively, the photosensitive material can be laminated to areceptor sheet, undergo exposure, and then wet processed. Both processesrequire development in an aqueous medium.

In U.S. Pat. No. 4,489,154, a process is claimed which produces a singlelayer color proof without wet development. The photosensitive materialcomprises a stripable cover sheet; a colored photoadherent layer; anonphotosensitive organic contiguous layer; and a sheet support. Thematerial is exposed and peel developed. The positive or negative imageis transferred to a receiver base. A fresh layer of adhesive must beapplied to the receptor for each subsequent transfer.

SUMMARY OF THE INVENTION

The present invention provides a positive-acting proofing method whichcomprises, in order:

(A) providing a photosensitive element which comprises, in order:

(i) a transparent support preferably having an adhesion promotedsurface; and

(ii) a single photosensitive composition layer on said preferablyadhesion promoted surface, which photosensitive layer comprises anorganic binding resin, a colorant, a photoinitiator, and a free radicalpolymerizable acrylate or methacrylate component having at least twoethylenically unsaturated groups, wherein said binding resin is presentin sufficient amount to bind the composition components into a uniformfilm, and wherein said colorant is present in sufficient amount touniformly color the composition, and wherein said photoinitiator ispresent in sufficient amount to initiate the free radical polymerizationof said polymerizable component upon exposure to sufficient actinicradiation, and wherein said polymerizable component is present insufficient amount to provide image differentiation when the compositionis image-wise exposed to actinic radiation; and

(iii) an adhesive layer directly adhered to said colored, photosensitivelayer, which adhesive layer comprises a thermoplastic resin which has aT_(g) in the range of from about 25° C. to about 100° C.; and

(B) either

(i) providing a receiver base to which said adhesive layer is laminatedat elevated temperature and pressure; and then image-wise exposing saidphotosensitive composition through the transparent support to actinicradiation; or

(ii) image-wise exposing said photosensitive composition to actinicradiation; and then providing a receiver base to which said adhesivelayer is laminated at elevated temperature and pressure; and

(C) peeling apart said support and said receiver base, therebytransferring the adhesive layer and the image-wise nonexposed portionsof the colored, photosensitive composition to the receiver base whilethe image-wise exposed portions remain on the adhesion promoted surfaceof the support; and

(D) optionally repeating steps (A) through (C) at least once withanother photosensitive element having at least one different coloranttransferred to the adhesive layer and image-wise nonexposed portions ofthe previously processed photosensitive element on said receiver base.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the usual full color proofing guide, four distinct colored images areformed, namely magenta, cyan, yellow, and black. When the images aresuperimposed upon each other, a simulated full color reproductionresults. As hereinbefore described, one begins the process of thepresent invention by preparing a photosensitive element which has asupport and sequentially carried thereon a colored, photopolymerizablelayer and then a thermoplastic adhesive layer.

In the preferred embodiment, the support may be composed of any suitableflexible sheet material provided it is transparent to the actinicradiation for the photopolymerizable layer. It should also preferably bedimensionally stable when treated with the herein specified processes.That is, it should have substantially no change in dimensions underheating in the range of approximately 60° C. to 120° C. duringlamination. One preferred material is polyethylene terephthalate. In theusual case, it has a thickness of approximately 20 to 200 um and a morepreferred thickness of approximately 50 to 80 um. The surface of thesupport may be smooth or it may be provided with a matte texture as onMelinex 475, which is available from ICI. A smooth surface is preferredbecause it does not scatter the actinic radiation and thereby does notreduce the resolution capability of the photosensitive layer. Suitablefilms with smooth surfaces nonexclusively include Melinex 054, 504, 505and 582 available from ICI, and Hostaphan 4400, 4500, and 4540 availablefrom Hoechst Celanese Corporation.

The preferred films are surface modified on one side or on both sides.Such modifications of the transparent support are preferred to increasethe adhesion of the exposed areas of the photosensitive coating to thesupport. This results in an improved dot reproduction. Therefore, asdefined within the context of this invention, an adhesion promotedsurface is one wherein the surface has been modified to make it morereceptive to the light exposed areas of the photosensitive coating. Suchsurface modifications include using a flame, electrical discharge,chemical etch, and surface coatings.

The surface coatings for adhesion promotion modify the surface withoutcontributing any mechanical or optical film properties of their own.They are commonly incorporated during the manufacturing process of thesupport. They may be monomolecular thick but are generally severallayers thick. The dried surface coatings are extremely thin, preferablybetween about 0.001 um and about 0.1 um, and therefore not selfsupporting. They are strongly bonded t the transparent support such thatthese surface coatings completely remain with the support during peeldevelopment. In other words, they are not partially nor wholly removedfrom the support during peel development. Examples of surface modifyingcoatings are disclosed in U.S. Pat. Nos. 3,751,280; 3,819,773;4,066,820; 4,098,952; 4,391,767; 4,486,483: 4,493,872; and 4,515,863.The preferred surface coating is a crosslinked polymer or copolymer ofacrylic acid or methacrylic acid or their esters with a thickness ofabout 0.003 um.

The adhesion promoter is by definition not an adhesive. An adhesive isdefined for the purpose of this invention to be a material which flowsand wets both surfaces of the elements to which it adheres and fills inthe gap of their surfaces under suitable conditions of temperature andpressure. An adhesion promoter may act in this manner when it is appliedto one surface but does not flow to the other surface.

Coatings which are thicker than 0.1 um are not suitable for thisapplication because thick surface coatings change the mechanicalproperties of the support and interfere with the optical clarity of thesupport. They may also absorb monomers from the photosensitive layer,cohesively fail during peel development, release from the support duringpeel development, and prevent good adhesion of subsequent adhesivelayers.

The colored, photosensitive layer is applied from a solvent coatingcomposition to the support, preferably to the adhesion promoted side ofthe support. Organic solvents are preferred for the photosensitivecoating because of the diverse solubility characteristics of the variouscomponents. Typical solvents nonexclusively include methyl ethyl ketone,2-methoxyethanol, 1-methoxy-2-propanol, 4-hydroxy-4-methyl-2-pentanone,tetrahydrofuran, and gamma-butyrolactone.

A typical photosensitive layer comprises a photopolymerizable monomer,photoinitiator, colorant, binder, and optional ingredients.

The photopolymerizable material contained in the colored, photosensitivelayer preferably comprises an addition polymerizable, nongaseous(boiling temperature above 100° C. at normal atmospheric pressure),ethylenically unsaturated compounds containing at least two terminalethylenically unsaturated groups, and being capable of forming a highmolecular weight polymer by free radical initiated, chain propagatingaddition polymerization. Suitable polymerizable materials nonexclusivelyinclude triethylene glycol dimethacrylate, tripropylene glycoldiacrylate, tetraethylene glycol dimethacrylate, diethylene glycoldimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanedioldimethacrylate, pentaerythritol tetraacrylate, trimethylol propanetriacrylate, trimethylol propane trimethacrylate, di-pentaerythritolmonohydroxypentaacrylate, pentaerythritol triacrylate, bisphenol Aethoxylate dimethacrylate, trimethylolpropane ethoxylate triacrylate,and trimethylolpropane propoxylate triacrylate.

Free radical liberating photoinitiators include any compound whichliberate free radicals on stimulation by actinic radiation. Preferredphotoinitiators nonexclusively include quinoxaline compounds asdescribed in U.S. Pat. No. 3,765,898; the vicinal polyketaldonylcompounds in U.S. Pat. No. 2,367,660; the alpha-carbonyls in U.S. Pat.Nos. 2,367,661 and 2,367,670; the acyloin ethers in U.S. Pat. No.2,448,828; the triarylimidazolyl dimers in U.S. Pat. No. 3,479,185; thealpha-hydrocarbon substituted aromatic acyloins in U.S. Pat. No.2,722,512; polynuclear quinones in U.S. Pat. Nos. 2,951,758 and3,046,127; and s-triazines in U.S. Pat. No. 4,656,272.

Dyes and/or pigments are included in the photosensitive layer to providecolor to the image areas. Preferred colorants for this invention arepigments rather than dyes. Light fast colorants are preferred. Thepigments are typically dispersed with an organic binder in an organicsolvent or mixture of organic solvents. The pigments may be organic orinorganic. They are ground to a small enough particle size to duplicatethe particle size and color of equivalent inks. The median diameter isgenerally less than 1 um.

Nonexclusive examples of colorants usable in the present invention areas follows: Permanent Yellow G (C.I. 21095), Permanent Yellow GR (C.I.21100), Permanent Yellow DHG (C.I. 21090), Permanent Rubine L6B (C.I.15850:1), Permanent Pink F3B (C.I. 12433), Hostaperm Pink E (73915),Hostaperm Red Violet ER (C.I. 46500), Permanent Carmine FBB (12485),Hostaperm Blue B2G (C.I. 74160), Hostaperm Blue A2R (C.I. 74160), andPrintex 25. Most of these pigments are products of Hoechst AG. They canbe used separately or blended for a desired color.

The photosensitive layer also contains a binder which not onlydetermines the hardness and/or flexibility of the coating but is alsoused to control the dry development. For example, the colored layer willremain with its support in the exposed and nonexposed areas if thebinder readily adheres to the adhesion promoted surface and if too muchof this type of binder is used. If the binder readily releases from thesurface and if too much of this type of binder is used, then the coloredlayer will be totally transferred with the adhesive layer.

Binders found suitable for the photosensitive layer are styrene/maleicanhydride copolymers and their half esters; acrylic polymers andcopolymers; polyamides; polyvinyl pyrrolidones; cellulose and itsderivatives; phenolic resins; and the like. The most preferred bindersare polyvinyl acetals, such as polyvinyl butyral and polyvinylpropional. The most preferred binders are polyvinyl formals which arecommercially available from Monsanto as Formvar. The formal content ofthe polyvinyl formals is approximately 65% to 86% expressed as percentpolyvinyl formal. The acetate content is approximately 9% to 30%expressed as percent polyvinyl acetate. The hydroxyl content isapproximately 5% to 7% as expressed as percent polyvinyl alcohol. Theaverage molecular weight is between 10,000 and 40,000.

Dyes may be included to spectrally sensitize the photoinitiator, such asdescribed in U.S. Pat. Nos. 4,282,309 and 4,454,218, and European PatentApplications 0,179,448 and 0,211,615.

Other ingredients which may be present in the photosensitive layer arethermal polymerization inhibitors, plasticizers, oligomers, residualsolvents, surfactants, inert fillers, antihalation agents, hydrogen atomdonors, photoactivators, and optical brightening agents.

In the preferred embodiment, the dry photosensitive layer has a coatingweight range between approximately 0.1 and 5 g/m². The more preferredcoating weight is between approximately 0.4 to 2 g/m².

In the practice of the present invention, the photopolymerizable monomercomponent is preferably present in the photosensitize layer in an amountranging from approximately 10% to 60% based on the weight of the solidsin the layer. A more preferred range is from approximately 15% to 40%.

In the practice of the present invention, the photoinitiator componentis preferably present in the photosensitive layer in an amount rangingfrom approximately 2% to 30% based on the weight of the solids in thelayer. A more preferred range is from approximately 6% to 20%.

In the practice of the present invention, the colorant component ispreferably present in the photosensitive layer in an amount ranging fromapproximately 10% to 50% based on the weight of the solids in the layer.A more preferred range is from approximately 15% to 35%.

In the practice of the present invention, the binder component ispreferably present in the photosensitive layer in an amount ranging fromapproximately 10% to 75% based on the weight of the solids in the layer.A more preferred range is from approximately 20% to 50%.

The adhesive layer is next applied to the photosensitive layer. Itspurpose is to aid in the transfer of the coating composite and toprotect the integrity of underlying, previous formed images during drydevelopment of subsequent layer(s). The application of the adhesive maybe accomplished in several different ways. For example, some adhesivesmay be coated on top of the photosensitive layer out of organic solventswhich do not have any solubilizing or deleterious effect on thephotosensitive layer. Such solvents can include cyclohexane, n-heptane,and n-hexane. Other adhesives may be coated out of water mixtures.Acrylic copolymers with high acid numbers, such as Carboset 525 from B.F. Goodrich, can be coated out of ammonium hydroxide:water mixtures.Alternatively, some adhesives may be coated as aqueous emulsions.Examples of aqueous emulsions include vinyl acetate copolymers such asMowilith DM-6 and DM-22 from Hoechst AG, and Vinac XX-210 and 465 DEVfrom Air Products. Some adhesives may be applied by hot melt extrusion.Suitable adhesives for this method of application include theethylene/vinyl acetate copolymers, such as Elvax 40-W and 150-W from DuPont.

The adhesive layer is distinguishable from the adhesion promotedsurface. The adhesive layer is defined for the purpose of this inventionas a layer consisting of an adhesive which flows and wets both surfacesof the elements to which it adheres and fills in the gaps of theirsurfaces under suitable conditions. Adhesive layers are generallythicker than 1 um.

The preferred method for applying the adhesive to the photosensitivelayer is by laminating the two together under elevated pressure and/ortemperature. The adhesive is initially coated onto a temporary support.The dried adhesive may then be transferred directly to thephotosensitive layer. The temporary support is removed, and then theadhesive with the photosensitive layer and support is laminated to areceiver base. Alternatively, the dried adhesive may be laminated to areceiver base. The temporary support is removed, and the photosensitivelayer with support is laminated to the adhesive on the receiver base.

Acrylic polymers and copolymers are preferred for the lamination methodfor applying the adhesive to the photosensitive layer. Vinyl acetatepolymers and copolymers are more preferred for this lamination method.Polyvinyl acetates are available from Hoechst AG as Mowilith. Theseresins have a average molecular weight between 35,000 and 2,000,000.They have a softening temperature between 80° C. and 180° C. In thepreferred embodiment, the polyvinyl acetate is present in the adhesivelayer in an amount of greater than approximately 50 percent by weight.The adhesive resin should have a softening temperature in the range ofapproximately 40° C. to 200° C., more preferably 60° C. to 120° C. Thelayer may optionally contain such other desired components as UVabsorbers, antistatic compositions, optical brighteners, andplasticizers. Suitable plasticizers include phthalates, nonexclusivelyincluding bibutyl phthalate, butyl benzyl phthalate, and dimethylphthalate. Polymeric plasticizers, such as Resoflex R-296 available fromCambridge Industries, may also be used. The plasticizer may be presentin the adhesive layer in an amount of up to approximately 30 percent byweight.

In the preferred embodiment, the dry adhesive layer has a coating weightrange between approximately 2 and 30 g/m². The more preferred coatingweight is between approximately 4 and 15 g/m². The thickness of theadhesive may be adjusted to regulate the apparent dot size of the finalproof.

Receiver bases may comprise virtually any material which can withstandthe laminating and dry development processes. White plastic sheets, suchas adhesion promoted, filled polyethylene terephthalate Melinex 3020from ICI, are useful for this purpose. Plastic coated paper sheets, suchas polyethylene coated paper from Schoeller, may also be used. Otherbases may include wood, glass, metal, and the like.

Lamination may be conducted by putting the two materials in contact andthen introducing the materials into the nip of a pair of heatedlaminating rollers under suitable pressure. Suitable laminatingtemperatures usually range from approximately 60° C. to 120° C.,preferably from 70° to 100° C.

The photosensitive layer is exposed by means well known in the arteither before or after the adhesive layer is applied to thephotosensitive layer. Exposure is preferably after the adhesive isapplied to the photosensitive layer, and more preferably after theadhesive and photosensitive layers have been laminated to the receiverbase. Such exposure may be conducted by exposure to actinic radiationfrom a light source through a conventional halftone positive colorseparation under vacuum frame conditions. Mercury vapor discharge lampsare preferred over metal halide lamps. Other radiation sources, such ascarbon arc, pulsed xenon, and lasers, may also be used. Light absorbingfilters may be used to reduce light scattering in the materials.

After lamination of the adhesive layer with the photosensitive layer andits support to the receiver base and after exposure of thephotosensitive layer, the photosensitive layer is dry developed bystripping the support from the receiver base at room temperature with asteady, continuous motion. No devices are necessary to hold down thereceiver base during stripping because only moderate manual peelingforces are needed to separate the materials. The preferred peel anglerelative to the peel direction is greater than 90°. The delaminationleaves the photoexposed areas on the support and the nonexposed areas onthe adhesive layer. The adhesive layer typically remains with thereceiver base. Thus, a positive image with the adhesive remains on thereceiver base.

Another photosensitive layer is laminated via another adhesive to thefirst image on the receiver base. The second photosensitive layer haspreferably a different color than the first and is exposed through theappropriate color separation. After lamination to the receiver andexposure, the support of the second photosensitive layer is removed aswas done with the first support. The second positive image with itsadhesive remains with the first image. A third and a fourth image may beadded in a manner similar to that used to produce the second image. Inthe usual case, four colored layers are employed to produce a full colorreproduction of a desired image. These four colors are cyan, magenta,yellow, and black.

A matte finish of the final image may be obtained by embossing theshiny, top surface of the image with a matte material, such as Melinex377 from ICI. This is done by laminating together the final image andmatte material. The matte material is then generally removed afterlamination. The advantage of this method is that the finish of the finalproof can be determined by careful selection of the matting material.

The final four color proof may be given a uniform, blanket exposure tophotoharden the nonexposed, colored areas on the receiver base. Aprotective layer may also be laminated on top of the last dry developedlayer.

The following nonlimiting examples serve to illustrate the invention.

EXAMPLE 1

The formulations for the photosensitive layers include the followingingredients in parts by weight, as indicated.

    ______________________________________                                                       Cyan Yellow  Magenta  Black                                    ______________________________________                                        Tetrahydrofuran  200    200     200    200                                    4-Hydroxy-4-methyl-2-penta-                                                                    150    150     150    150                                    none                                                                          1-Methoxy-2-propanol                                                                           444    465     489    490                                    gamma-Butyrolactone                                                                            44      65      89     90                                    Formvar 12/85    6       13      18     9                                     Di-pentaerythritol                                                                             8       12      8      12                                    monohydroxy pentaacrylate                                                     2,3-di(4-methoxyphenyl)quin-                                                                   4       4       4      4                                     oxaline                                                                       Hostaperm B2G    7      --      --     --                                     Permanent Yellow GR                                                                            --      7      --     --                                     Permanent Red FBB                                                                              --     --       12    --                                     Printex 25       --     --      --      11                                    ______________________________________                                    

The pigments are introduced into the above solutions as dispersions.They are dispersed with some of the Formvar binder in a 1:1 solventmixture of 1-methoxy-2-propanol: gammabutyrolactone. They are ground tothe proper particle size for the correct transparency. The mediandiameter is less than 0.2 um. For each color, the ingredients arethoroughly mixed together and coated onto the adhesion promoted surfaceof a 63 um thick sheet of Melinex 528. This transparent polyethyleneterephthalate film has an antistat treatment on the side opposite to theadhesion promoted side. This film base is commercially available fromICI. The coatings are dried at 93° C. to give optical densities of 1.3,0.9, 1.3, and 1.6 for cyan, yellow, magenta, and black, respectively.

The formulation for the adhesive layer includes the followingingredients in parts by weight, as indicated.

n-Butyl acetate: 78

Resoflex R-296: 1

Mowilith 30: 21

The adhesive ingredients are thoroughly mixed and coated onto thenontreated side of four sheets of 67 um thick Hostaphan 4756, which is apolyethylene terephtalate film with an antistat treatment on the otherside. This film base is available from Hoechst Celanese. The coating isdried at 93° C. to a coating weight of 12 g/m².

The adhesive layer is applied to the cyan photosensitive layer bylaminating the two materials together at 85° C. The temporary supportfor the adhesive is removed, leaving the adhesive layer on thephotosensitive layer. Next, the photosensitive composite is laminatedvia the adhesive layer to a receiver base, in particular, a 145 um thicksheet of Melinex 3020. The photosensitive layer of the transferredcomposite is then image-wise exposed to actinic light through a cyanpositive color separation and through the transparent support. After theexposure, the transparent support is removed from the receiver base,thereby removing the image-wise exposed portions with the support whileleaving the adhesive layer and the image-wise nonexposed portions of thecyan photosensitive layer on the white receiver base.

Another adhesive layer is applied to the magenta photosensitive layerand its temporary support is removed from the photosensitive composite.Next, the composite is laminated on top of the first, cyan image andthen image-wise exposed for an exposure duration equal to that for thecyan photosensitive layer. After the exposure, the support is removed,revealing the magenta image on top of the cyan image. This method isrepeated for the yellow photosensitive layer and then for the blackphotosensitive layer. A full, four color reproduction is produced whichgives an accurate representation of the original from which theseparations are prepared. The circular resolving power for equal linesand spaces using these photosensitive layers is 15 um. The dotreproduction range is 2% to 98% with a 60 line/cm screen.

EXAMPLE 2

The formulations in Example 1 are used in this example. However in thiscase, the solutions for the photosensitive layers are coated onto 75 umthick sheets of Melinex 505, which is an adhesion promoted, transparentpolyethylene terephthalate film commercially available from ICI. Thesolution for the adhesive layer is coated onto 75 um thick sheets ofMelinex 516, which is a slip treated polyethylene terephthalate filmfrom ICI. The adhesive layer is laminated to a 145 um thick receiverbase of Melinex 3020. The temporary support for the adhesive is manuallypeeled off, leaving the adhesive layer on the white receiver base. Next,the cyan photosensitive layer with its support is brought in contactwith the transferred adhesive layer. The two materials are thuslaminated together at 85° C. The photosensitive layer is then image-wiseexposed to actinic light through a cyan positive color separation andthrough the support. The cyan photosensitive layer is subsequently drydeveloped by the removal of the support from the receiver base.

Another adhesive layer is laminated on top of the first, cyan image. Thetemporary support for the adhesive is removed. Next, the magentaphotosensitive layer with its support is laminated to the secondadhesive. After forming the photosensitive composite, the magentaphotosensitive layer is image-wise exposed. The magenta image is formedby peel development like the cyan image. This is repeated for the yellowphotosensitive layer and then for the black photosensitive layer. Thismethod produces a full, four color reproduction.

EXAMPLE 3

The formulations for the photosensitive layers in Example 1 are used inthis example. However, the formulation for the adhesive layer includesthe following ingredients in parts by weight, as indicated.

n-butyl acetate: 85

Mowilith 60: 15

The photosensitive solutions are coated onto Melinex 505 and theadhesive solution is coated onto Melinex 516.

The adhesive layer is transferred to the cyan photosensitive layer,which is then image-wise exposed. The exposed photosensitive articlewith its latent image is then laminated to polyethylene coated paper.Next, the cyan photosensitive layer is peel developed.

Another adhesive layer is transferred to the magenta photosensitivelayer. This composite is then exposed, laminated to the first, cyanimage, and subsequently peel developed. The yellow and blackphotosensitive layers are likewise processed to produce a four colorproof.

EXAMPLE 4

The formulations for the photosensitive layers include the followingingredients in parts by weight, as indicated.

    ______________________________________                                                            Yellow                                                                              Magenta                                             ______________________________________                                        Tetrahydrofuran       200     200                                             4-Hydroxy-4-methyl-2-pentanone                                                                      150     150                                             1-Methoxy-2-propanol  444     465                                             gamma-Butyrolactone    44      65                                             Formvar 7/95           5       9                                              Di-pentaerythritol     12      8                                              monohydroxy pentaacrylate                                                     2,3-di(4-methoxyphenyl)quinoxaline                                                                   4       4                                              Permanent Yellow GR    7      --                                              Permanent Red FBB     --       12                                             ______________________________________                                    

The formulation for the adhesive is the same as that in Example 1. Thephotosensitive solutions are coated onto Melinex 505 and the adhesivesolution is coated onto Melinex 516.

Adhesive layers are transferred to the yellow and magenta photosensitivelayers. The magenta photosensitive composite is first transferred toMelinex 3020. This composite is then image-wise exposed and drydeveloped. Next, the yellow photosensitive composite is laminated to themagenta image. This is then image-wise exposed and dry processed toproduce a two color progressive proof.

EXAMPLE 5

The formulations in Example 1 are used in this example. The ingredientsfor the photosensitive layer are thoroughly mixed and coated onto theadhesion promoted surface of 75 um thick sheets of Melinex 505 to giveoptical densities of 1.3, 0.9, 1.3, and 1.6 for cyan, yellow, magenta,and black, respectively.

The adhesive ingredients for the adhesive layer are thoroughly mixed andcoated onto the slip treated surface of 75 um thick sheets of Melinex516 to a dry coating thickness of 10 um. The adhesive layers aretransferred to the four different photosensitive layers. The Melinex 516sheets are removed, providing composites with the photosensitive layerbetween the adhesive layer and the Melinex 505. The magentaphotosensitive composite is first transferred to a 145 um thick sheet ofMelinex 3020. This composite is then image-wise exposed and drydeveloped. Next, the yellow photosensitive composite is laminated to themagenta image. This is then exposed and processed. The black compositeand then the cyan composite are exposed and processed in a like manner.A full, four color reproduction is produced which gives an accuraterepresentation of the original from which the separations were prepared.The circular resolving power for equal lines and spaces using thesephotosensitive layers is 15 um. The dot reproduction range is 2 to 98%with a 60 line/cm screen.

COMPARATIVE EXAMPLE A

The materials in this comparative example are similar to those inExample 5, except that the transparent support for this comparativeexample is a 75 um thick sheet of Melinex 516. This transparentpolyethylene terephthalate support does not have an adhesion promotedsurface. The chemical formulations and processing are the same as thoseused in Example 5. Optimum exposure for the comparison photosensitivecomposites is four times that used in Example 5.

A four color reproduction which is produced with the comparativematerials is inferior to that made in Example 5. The circular resolvingpower is less, at 25 um. The dot reproduction range is narrower, at 5 to90% with a 60 line/cm screen.

COMPARATIVE EXAMPLE B

The materials in this comparative example are similar to those inComparative Example A, except that an additional adhesive layer isbetween the photosensitive layer and the transparent support. Thus thecomposites consist of, in the following order, a transparentsupport/additional adhesive layer/photosensitive layer/adhesive layer.The additional layer has the same thickness and chemical composition asthe regular layer in Comparative Example A. The processing is the sameas that used for Comparative Example A.

A four color reproduction which is produced with the materials from thiscomparative example is unacceptable due to residual colorants in thenonimage areas. This background stain is due to separation between thetransparent support and the additional adhesive layer during peeldevelopment. In Example 5 and Comparative Example A, the coloredphotosensitive layers separate from the transparent supports in thenonexposed areas and from the adhesive layers in the exposed areas.

EXAMPLE 6

The formulations for the photosensitive layers include the followingingredients in parts by weight, as indicated.

    ______________________________________                                                      Cyan  Yellow  Magenta  Black                                    ______________________________________                                        Tetrahydrofuran 200     200     200    200                                    4-Hydroxy-4-methyl-2-penta-                                                                   150     150     150    150                                    none                                                                          1-Methoxy-2-propanol                                                                          444     465     489    490                                    gamma-Butyrolacton                                                                            44      65      89     90                                     Formvar 12/85   5       9       10     9                                      Di-pentaerythritol                                                                            8       12      8      12                                     monohydroxy pentaacrylate                                                     4,4-Bis(dimethylamino)ben-                                                                    2       2       2      2                                      zophenone                                                                     2-Mercaptobenzothiazole                                                                       2       2       2      2                                      Bis(2,4,5-triphenyl)imidazole                                                                 4       4       4      4                                      Hostaperm B2G   7       --      --     --                                     Permanent Yellow GR                                                                           --      7       --     --                                     Permanent Red FBB                                                                             --      --      12     --                                     Printex 25      --      --      --     11                                     ______________________________________                                    

The formulation for the adhesive is the same as that in Example 1. Thephotosensitive solutions are coated onto Melinex 505 and the adhesivesolution is coated onto sheets of Melinex 516.

The adhesive layers are transferred to the cyan, yellow, magenta, andblack photosensitive layers. The cyan photosensitive composite is firsttransferred to Melinex 3020 via the adhesive layer. This photosensitivecomposite is then image-wise exposed and dry developed. Next, themagenta photosensitive composite is laminated to the cyan image. This isthen exposed and processed. The yellow composite and then the blackcomposite are exposed and processed in a like manner.

EXAMPLE 7

The photosensitive formulations in Example 6 are used in this example.The photosensitive solutions are coated onto the adhesion promoted sideof four sheets of Melinex 528. The adhesive formulation in Example 3 isused in this example. The adhesive ingredients are thoroughly mixed andcoated onto four sheets of Melinex 516 to a dry coating thickness of 10um. As in Example 6, the adhesive layers are transferred to the coloredphotosensitive layers. The composites are then sequentially transferredto a sheet of Melinex 3020, image-wise exposed, and dry developed.

A full, four color reproduction is produced which gives an accuraterepresentation of the original from which the separations were prepared.The circular resolving power for equal lines and spaces using thesephotosensitive layers is 15 um. The dot reproduction range is 2 to 98%with a 60 line/cm screen.

COMPARATIVE EXAMPLE C

The materials in this comparative example are similar to those inExample 7, except that the photosensitive ingredients are coated ontothe antistat side of the Melinex 528 sheets, instead of the adhesionpromoted side of the sheets. The chemical formulations and processingare the same as those used in Example 7.

A four color reproduction which is produced with the materials from thiscomparative example is unacceptable due to residual colorants in thenonimage areas. This background stain is due to separation between theantistat side of the transparent support and the colored photosensitivelayer in the exposed and nonexposed areas during peel development. InExample 7, the colored photosensitive layer separates from the adhesionpromoted surface of the film in the nonexposed areas and from theadhesive layer in the exposed areas.

What is claimed is:
 1. A method for forming a colored image whichcomprises, in order:(A) providing a photosensitive element whichcomprises, in order:(i) a transparent support having an adhesionpromoted surface; and (ii) a single photosensitive composition layerdirectly on said adhesion promoted surface, which photosensitive layercomprises an organic binding resin, a colorant, a photoinitiator, and afree radical polymerizable acrylate or methacrylate component having atleast two ethylenically unsaturated groups, wherein said binding resinis present in sufficient amount to bind the composition components intoa uniform film, and wherein said colorant is present in sufficientamount to uniformly color the composition, and wherein saidphotoinitiator is present in sufficient amount to initiate the freeradical polymerization of said polymerizable component upon exposure tosufficient actinic radiation, and wherein said polymerizable componentis present in sufficient amount to provide image differentiation whenthe composition is image-wise exposed to actinic radiation; and (iii) anadhesive layer directly adhered to said colored, photosensitive layer,which adhesive layer comprises a thermoplastic resin which has a T_(g)in the range of from about 25° C. to about 100° C.; and (B) either(i)providing a receiver base to which said adhesive layer is laminated atelevated temperature and pressure; and then image-wise exposing saidphotosensitive composition through the transparent support to actinicradiation; or (ii) image-wise exposing said photosensitive compositionto actinic radiation; and then providing a receiver base to which saidadhesive layer is laminated at elevated temperature and pressure; and(C) peeling apart said support and said receiver base, therebytransferring the adhesive layer and the image-wise nonexposed portionsof the colored, photosensitive composition to the receiver base whilethe image-wise exposed portions remain on the adhesion promoted surfaceof the support; and (D) optionally repeating steps (A) through (C) atleast once with another photosensitive element having at least onedifferent colorant transferred to the adhesive layer and image-wisenonexposed portions of the previously processed photosensitive elementon said receiver base.
 2. The method of claim 1 wherein said transparentsupport comprises polyethylene terephthalate.
 3. The method of claim 1wherein said adhesion promoted surface comprises a surface coating of acrosslinked polymer or copolymer of acrylic acid or methacrylic acid ortheir esters.
 4. The method of claim 3 wherein said surface coating hasa thickness of from about 0.001 to about 0.1 um.
 5. The method of claim1 wherein said photosensitive composition comprises one or more monomersselected from the group consisting of triethylene glycol dimethacrylate,tripropylene glycol diacrylate, tetraethylene glycol dimethacrylate,diethylene glycol dimethacrylate, 1,4-butanediol diacrylate,1,6-hexanediol dimethacrylate, pentaerythritol tetraacrylate,trimethylol propane triacrylate, trimethylol propane trimethacrylate,di-pentaerythritol monohydroxypentaacrylate, pentaerythritoltriacrylate, bisphenol A ethoxylate dimethacrylate, trimethylolpropaneethoxylate triacrylate, and trimethylolpropane propoxylate triacrylate.6. The method of claim 1 wherein said photosensitive compositioncomprises one or more photoinitiators selected from the group consistingof 2,3-di(4-methoxyphenyl)quinoxaline, 9-phenylacridine,bis(2,4,5-triphenyl)imidazole, and their derivatives.
 7. The method ofclaim 1 wherein said photosensitive composition comprises one or morecolorants selected from the group consisting of dyes and pigments. 8.The method of claim 1 wherein said photosensitive composition comprisesone or more binding resins selected from the group consisting ofstyrene/maleic anhydride copolymers and their half esters; acrylicpolymers and copolymers; polyamides; polyvinyl pyrrolidones; cellulosicresins; phenolic resins; and polyvinyl acetals.
 9. The method of claim 8wherein said polyvinyl acetal is a vinyl formal polymer or copolymercontaining vinyl formal.
 10. The method of claim 1 wherein saidphotosensitive composition further comprises one or more ingredientsselected from the group consisting of spectral sensitizers, thermalpolymerization inhibitors, plasticizers, oligomers, surfactants, inertfillers, antihalation agents, hydrogen atom donors, photoactivators, andoptical brightening agents.
 11. The method of claim 1 wherein thecoating weight of said photosensitive composition ranges from about 0.1g/m² to 5 g/m².
 12. The method of claim 1 wherein the acrylate ormethacrylate component is present in said photosensitive layer in anamount ranging from about 10% to about 60% by weight of thephotosensitive composition.
 13. The method of claim 1 wherein thephotoinitiator component is present in said photosensitive layer in anamount ranging from about 2% to about 30% by weight of thephotosensitive composition.
 14. The method of claim 1 wherein thecolorant component is present in said photosensitive layer in an amountranging from about 10% to about 50% by weight of the photosensitivecomposition.
 15. The method of claim 1 wherein the binder component ispresent in said photosensitive layer in amount ranging from about 10% toabout 75% by weight of the photosensitive composition.
 16. The method ofclaim 1 wherein said adhesive layer comprises one or more thermoplasticpolymers having a softening temperature in the range of about 40° C. toabout 200° C.
 17. The method of claim 1 wherein said adhesive layercomprises a vinyl acetate polymer or copolymer containing vinyl acetate.18. The method of claim 17 wherein polyvinyl acetate is present in thesaid adhesive layer in an amount of at least about 50% by weight of saidadhesive layer.
 19. The method of claim 1 wherein said adhesive layerfurther comprises a plasticizer.
 20. The method of claim 19 wherein saidplasticizer is polymeric.
 21. The method of claim 1 wherein saidadhesive layer further comprises one or more ingredients selected fromthe group consisting of UV absorbers, antistatic compositions, opticalbrighteners, and plasticizers.
 22. The method of claim 1 wherein thecoating weight of the said adhesive layer ranges from about 2 g/m² toabout 30 g/m².
 23. The method of claim 1 wherein the plasticizer ispresent in the said adhesive layer in an amount of up to about 30% byweight of said adhesive layer.
 24. The method of claim 1 wherein thesaid receiver base comprises paper, coated paper, or polymeric film. 25.The method of claim 1 wherein said lamination is conducted at atemperature of from about 60° C. to about 120° C.
 26. The method ofclaim 1 further comprising the subsequent step of providing a protectivecovering on the image-wise nonexposed portions of the photosensitivelayer on the receiver sheet.
 27. The method of claim 1 wherein step (D)is conducted three times to produce a four-color reproduction.
 28. Themethod of claim 27 further comprising the subsequent step of providing aprotective covering on the four-color reproduction.
 29. The method ofclaim 27 further comprising the subsequent step of a uniform blanketexposure to photoharden the nonexposed areas.
 30. The method of claim 1wherein said transparent support comprises polyethylene terephthalate;andsaid adhesion promoted surface comprises a crosslinked polymer orcopolymer of acrylic acid or methacrylic acid or their esters; and saidphotosensitive composition comprises one or more acrylate ormethacrylate components selected from the group consisting oftriethylene glycol dimethacrylate, tripropylene glycol diacrylate,tetraethylene glycol dimethacrylate, diethylene glycol dimethacrylate,1,4-butanediol diacrylate, 1,6-hexanediol dimethacrylate,pentaerythritol tetraacrylate, trimethylol propane triacrylate,trimethylol propane trimethacrylate, di-pentaerythritolmonohydroxypentaacrylate, pentaerythritol triacrylate, bisphenol Aethoxylate dimethacrylate, trimethylolpropane ethoxylate triacrylate,and trimethylolpropane propoxylate triacrylate; and said photosensitivecomposition comprises one or more photoinitiators selected from thegroup consisting of 2,3-di(4-methoxyphenyl)quinoxaline,9-phenylacridine, bis(2,4,5-triphenyl)imidazole, and their derivatives;and said photosensitive composition comprises one or more pigments; andsaid photosensitive composition comprises one or more binding resinsselected from the group consisting of vinyl acetal containing polymersand copolymers; and said adhesive layer comprises polyvinyl acetate.